Hourglass and the Time Traveller
by HelloSkye
Summary: Sans is stuck with the same boring job. Again. He wishes that the happiness his friends are feeling will last forever, but when he meets a mysterious figure that he vaguely remembers meeting, things start to spin out of hands... or, phalanges. When the girl with the hourglass charm decides to reveal the truth, how will the monsters react? Female Frisk.
1. Prologue

**A/N: I do not own Undertale. All rights to the characters, world, the game belongs to Toby Fox; although I wish I owned Sans. only OC is owned by me.**

* * *

Sans never thought he'd get along with the humans.

Welp, maybe except for the kid.

It had been a while since Frisk had destroyed the barrier and led the monsters back to the Surface. Things seemed to look brighter for the monsters, but what Flowey told Frisk turned out to be true.

Not all humans were nice. And the monsters learnt that the hard way.

Maybe except Undyne. But that's another story.

To be honest, he really couldn't care less. It wasn't something that he didn't expect, anyway. What had he thought of when he first came up to the Surface?

Oh, that's right. He didn't really have any thoughts. He just followed Papyrus.

And Frisk.

And Toriel.

And Asg- the point is, Sans was too much of a lazybones to think about anything related with Surface or humans.

Yes, the sunset was absolutely alluring when Frisk led the group to the Surface. The azure sky adorned with constantly changing, fluffy looking things called 'clouds' at daytime was a never-ending entertainment for Papyrus.

But that didn't matter too much for Sans.

What mattered to him was that he was with his friends. Snowdin was definitely his home, but when his friends wanted to move to the Surface, he had to follow.

After all, the skeleton brothers were inseparable.

The negotiation took long. Asgore, Toriel and Sans accompanied Frisk, the official ambassador of monsters.

Humans didn't believe that the ten-year-old kid was the ambassador. They also found it hard to believe that skeletons could talk and freaked out when Sans' left eye glowed blue dangerously.

And of course, he had to crack a pun to lift the mood.

"i should say, this situation is pretty-"

"Sans," Toriel warned quietly.

" _-humerus._ " He finished. Frisk silently face-palmed and Asgore gave a nervous smile to the humans ogling at the skeleton making skeleton puns. Which, just made the situation more awkward. Anyhow, the negotiation was made, and monsters were allowed to settle on the Surface.

Underworld was decided to be renovated as tourists' attraction. This obviously meant Sans' more-than-one-job-life was stuck with him. Frisk gave him a pat on the back, giving a small but encouraging smile as Sans groaned under his breath.

"so much for a brighter future."

* * *

By the time Frisk turned fifteen, Toriel and Asgore had moved in together, raising the human kid with showers of love. Papyrus and Undyne would often visit Frisk, offering their new culinary dishes that they invented.

Sans, he mostly stayed at his home on the Surface, or went down to Underworld to patrol the areas as the previous sentry. Frisk made sure to visit Flowey to keep him company, not that his reactions had any hospitality in them. Alphys was still figuring out how to save Asriel from the golden flower. The humans were warned to watch out for the golden flower that seemed very sweet.

Not that all humans were _brainy_ enough to stop their stupid curiosity. This meant Sans had to run around in circles, warding off idiots who were so keen on touching the moving flower.

It was all that same, boring, chasing-off-idiot kind of day. And then he met her.

A dark hooded figure that stood ever-so-silently in front of the echo flower. Never saying anything. Not moving. Just staring. The waterfall didn't have much of a breeze, but a gentle breeze weaved through the waters as Sans regarded the figure noiselessly, lowering the hoods of the enigmatic figure.

Raven coloured hair waltzing through the placid breeze. Streaks of silver white reflecting the dim, mysterious cerulean glow from the echo flowers. Cat-like eyes blinking slowly as if she was trying to register towers of information. The ever-changing amethyst orbs shifting shades to darker violet.

Sans was so sure that he had seen the girl before. But from where? Sharp pain hit his skull, and when he opened his eyes again to see what the human was doing, she was already gone.

The flowers echoed the barely-audible whisper as Sans approached.

"…History repeats itself…"

* * *

 **A/N: Really short. I wish I could write longer, but it's almost 3am where I am and I'm half asleep.**

 **I love critical readers. Leave a review if you have any ideas/suggestions or spot any mistakes I made.**

 **-HelloSkye-**


	2. Only the Beginning

**Disclaimer: I don't own Undertale (although I'd totally pay to own Sans). I only own the OC.**

 **A/N: Yay. Back with a new (and longer) chapter. It would be nice if you could read this chapter while listening to the Undertale soundtrack 71: Undertale. It's a beautiful song and it makes you think back to the choices that you made, how the monsters accepted you as the human who fell to the Underworld.**

 **I don't really like sad stories, but it's Undertale. It's a mix of sad and happy. This chapter might be confusing because I stopped writing for ages and came back. If you're confused, leave a review and I'll see whether I can change anything about the story :)**

 **Truthfully I thought I was going to focus on my OC only but because Undertale has so many characters that can be interpreted differently, I'll probably end up putting an extended stories for important characters.**

 **Because, let's admit it, I find all the characters lovable and unique.**

 **Anyway, let's cut the unnecessary chitchat and go straight to the chapter.**

* * *

Chapter 1: Only the Beginning

Sans wanted to forget about the girl. With the field of echo flowers constantly repeating the whisper of the girl, it was rather difficult for even laid back skeleton like him.

Of course, he would act like nothing's wrong when his friends are around.

But really, what was that girl?

Was it even possible for a human to move away that fast?

Have they ever met?

Why was she so familiar?

Questions after questions clouded his mind while he was carrying out multiple jobs at once. Papyrus seldom asked Sans if there was anything wrong and there would be a pun or two that made Papyrus regret talking to his older brother.

It wasn't hard, really. Staying as he is, just throwing his dad skeleton puns, wanting to be lazy. Nobody would see the difference. Sans made it sure that nobody would realise the change. They won't be able to _see through_ him (Pun not intended). Which is ironic, but really, nobody did.

Or maybe they did, but just didn't bother to tell.

Point was, Sans was too distracted to concentrate with his current jobs. There was no way that he could've forgotten the enchanting amethyst orbs if he had met the girl. He swore that he went through everything on his journal. It was impossible that the timeline could've reset even after Frisk had broken the barrier.

So what, exactly was that girl? Plopping down on his chair, scanning through his journal pages, Sans popped his neck joint when an odd writing caught his attention.

timeline resets itself History repeats itself

A writing that was crossed out and written with different words. With different handwriting. A small, intricate cursive that was distinct to his larger handwriting.

'History repeats itself' The whispers of echo flowers briefly flashed to his skull, sending chills down his spine.

But how? The human could not have been at Underworld. If she fell, Toriel would've given him a heads-up.

Was it coincidence?

Reading the journal didn't give him any clarification. It brought more questions to the surface. Closing his journal and locking it inside his drawer, Sans sighed deeply.

He hated not knowing.

* * *

Frisk was scared of Flowey. It was natural, really. Except that she couldn't blame Flower for being… soulless.

He would laugh at her compassion whenever she'd talk to him. Whispering dark, cruel words that would bring her back to the timelines when she'd make horrible, horrible choices.

It was tiring, really. Sometimes she wanted to give up. But she remembered Asriel. Alone, in front of the patch of golden flowers, with that bittersweet smile etched on his lips, explaining things slowly.

How he couldn't feel.

How she shouldn't worry about him, and that somebody will have to take care of the flowers.

That he doesn't want to break their hearts all over again, and that it's better off if they never see him.

Asking her why she's still there, giving a little sad smile as he enquired whether she was keeping him company as his round goat eyes watered.

Timidly questioning why, she climbed up Mt Ebott, despite the legend on the Surface. Telling her that only she'd know the answer.

And truthfully, she didn't know why.

Explaining about Chara. About hating humanity. And that Frisk was different from Chara, honestly admitting that she's the type of friend he wished to have.

The truth about why he turned into a flower. How he blamed himself for that decision. How it made him adapt the horrible view of the world, "kill or be killed". And that he doesn't regret his choice anymore.

To remember him as someone that was her friend for a little while. Warning her of the outside world. Telling her that there were lots of 'Floweys' out there. Pleading her to not kill, and not to be killed.

And really, she couldn't help but feel bad.

For not being able to save Asriel. Having to cry in his stead when Toriel and Asgore couldn't remember anything. Having to keep that guilt of not being able to tell the truth for fear that her parents would break down into pieces when they learn the cruel nature.

Talking to Flowey didn't help her feel better. But the little wavers, quivers of his voice from her kindness, his confusion as to why he couldn't bring himself to kill the girl, reminded her… that Asriel is still there somewhere, and that there was hope.

It was the exact same day. Frisk carrying a bottle of cold water, humming slightly, hoping to see his genuine smile this time.

What welcomed Frisk was a new sight.

Flowey cringing from a hooded figure, frightened. Pale hand extended to Flowey as if it wants to pet the flower. Instinctively, Frisk threw the water bottle to the figure.

It hit the figure square on its' head with a sharp noise. Water spilled to the ground as the glass bottle broke into pieces. Flowey's face whisked to Frisk in obvious relief. The figure stood up from kneeling position and Frisk swore that she saw a dim violet glow under the hood. Unexpectedly petite in full height, the figure wobbled a bit and Frisk noticed the droplets of blood on the gold petals of the flowers.

Oh my God. What has she done?

Horrified of what she's done, Frisk approached the figure cautiously.

"Uh-"

"Believe in yourself." Young, gentle voice hummed musically. To whom her voice was directed, Frisk had no idea. The dim violet glow was now bright amethyst, crescent-shaped underneath the hood.

"Your journey is yet to finish." Pale fingers brushed the tips of Flowey's petals and he looked close to crying. Familiar melody began to echo in Frisk's head.

Undertale. The amiable, mellow and pleasant tones that echoed as Frisk walked through the New Home. Memories flashed back to the time when the monsters that she spared came to tell her a tale, soft smile etched upon all their faces, thankful of your actions.

* * *

A long time ago, a human fell into the RUINS.

Injured by its fall, the human called out for help.

ASRIEL, the king's son, heard the human's call.

He brought the human back to the castle.

Overtime, ASRIEL, and the human became like siblings.

The King and Queen treated the human as their own.

The underground was full of hope.

Then one day…

The human became very ill.

The sick human had only one request.

To see the flowers from their village.

But there was nothing we could do.

The next day.

The next day.

...

The human died.

ASRIEL, wracked with grief, absorbed the human's soul.

He transformed into a being with incredible power.

ASRIEL reached the center of the village.

There, he found a bed of golden flowers.

He carried the human onto it.

Suddenly, screams rang out.

The villagers saw ASRIEL holding the human's body.

They thought that he had killed the child.

The humans attacked him with everything they had.

He was struck with blow after blow.

ASRIEL had the power to destroy them all.

But…

ASRIEL did not fight back.

Clutching the human. . .

ASRIEL smiled, and walked away.

Wounded, ASRIEL stumbled home.

He entered the castle, and collapsed.

His dust spread across the garden.

The kingdom fell into despair.

The king and queen had lost two children in one night.

The humans had once again taken everything from us.

The king decided to end our suffering.

Every human who falls down here must die.

With enough souls, we can shatter the barrier forever.

King ASGORE will let us go.

King ASGORE will give us hope.

King ASGORE will save us all.

You should be smiling too.

Aren't you excited?

Aren't you happy?

You're going to be free.

* * *

Frisk was free. Wasn't she? But why was it that her heart was feeling so empty? Why was it that she felt so guilty?

Sniffling a sob, Frisk looked at the figure. Flowey was talking to himself, confused, so lost.

"It's not your fault."

 _That you couldn't save Asriel._

The small echo in her head finished the sentence that the figure didn't bother finishing. Hesitantly placing a hand on Frisk's head, the figure gave a gentle pat.

"It's not over yet." And then silently as ever, the figure was gone. The only thing that caught Frisk's eyes was an intricate miniature hourglass charm, softly glowing cobalt blue under the shadows.

"Remember, your journey's yet to be finished." Melodic voice echoed as Frisk was left to sob. Even Flowey, not knowing how to feel, was looking upset than he could ever be.

* * *

 **Thank you all for reading! As I said before, I love critical readers. Leave a review if you spot anything weird or off about my story. Thanks heaps!**

 **-HelloSkye-**


	3. Unexpected Turn

**Disclaimer: I don't own Undertale. All credits go to Toby Fox. the only thing I own is my OC :)**

 **A/N: another chapter! I've been busy trying to move & write, which is bothersome. Lack of sleep isn't helping either, but I'm hoping to get this story done (although I doubt it's going to finish soon). Feel free to ask any questions and if you spot a typo or punctuation mistake, please let me know! **

* * *

Chapter 2: Unexpected Turn

Frisk ran back to the Surface, her breath billowing like a cloud in the cold winter air. For some reason, she felt like she knew the person. The figure's voice, the familiar violet glow… it made her wanting to cry. Feeling her eyes burn, Frisk wiped her eyes roughly as she kept on running when-

"woah, kid. what's making you run like this?" Sans was lifting you up with his magic, his blue jacket and black basketball shorts on like always. Frisk looked down to meet the white pinpoints in his eyesockets, trying to catch her breath when-

"kid, did you cry?" his piercing stare meant that there was no lying. Frisk opened her mouth to answer no, but closed quickly to nod.

"and allow me to ask why the hell-" oh no, Sans' voice was getting dangerously low. That meant bad. "-are there bloodstains on your shoes?"

Crap. Frisk craned her neck to see her light grey sneakers stained with crimson. She gave a nervous laugh as Sans regarded her with his cold gaze. She squirmed mid-air and opened her mouth slightly to close it back and signed to him.

[Um, put me down… please?] The ice blue glow died as he gently put her down. She grinned good-naturedly and gulped as his piercing look met her eyes again.

Knowing that she won't be able to lie to the skeleton, Frisk explained what has happened. The hooded figure with amethyst orbs. An hourglass charm that glowed blue when she disappeared. That she was trying to approach Flowey, but excluding the parts where she had talked her. Sans' eyes widened.

"you met the girl?"

[You know her?] Frisk signed to him and he nodded.

"not personally, but i've seen her around." She decided not to poke more than that after looking at his expression. Silence passed. And then the sharp ring on her phone scared the life out of her.

"Mum?" Toriel's pleasant voice was heard from the other side and Frisk smiled gently. Frisk could hear the gentle music in that background that her mum would play in home. She could also hear the hesitancy in her voice as Toriel tried to say something.

"Frisk, would you be kind to go grocery shopping? I realised we're missing some of the ingredients." Her mum sounded apologetic; and Frisk gave a gentle laugh. Was she feeling bad just for asking that? With a soft smile etched on her lips, Frisk nodded into the phone.

"Yeah, sure. Text me the list, okay?" Sans' piercing white glow followed Frisk's cell as she pocketed it. Frisk mumbled as she cringed away from his glare.

"I need to go grocery shopping."

"ok." Short silence followed and Sans opened his mouth again.

"kid, you wanna talk after that?" Frisk couldn't say no. Especially when she knew that Sans was not the one to take no with the expression he had on his face. She nodded. He held out his arm to her, opening his mouth.

"let's take the shortcut, shall we?"

* * *

The dark hood lowered and feeling the cold breeze on her pale cheeks, the girl swung her legs like a kid as she sat on the tall branch of the tree. The girl's amethyst hues followed the skeleton and a young girl beside him, holding grocery bags in their hands. The familiarity of the skeleton made her heart sink, remembering how she should be operating.

 _Never meet them in person. Help them with little hints, but never ever, appear in front of them. You're invisible._

So much for that promise. She'd been seen by the two people that she should be most careful of. Burying her face into her cold hands, the girl sighed deeply.

What has she gotten herself into?

Would she be able to make any difference? She wondered, thinking of the words the monster had told her before she left.

'the smallest thing can bring chaos when it's to do with time.'

The small sorrowful smile that he gave. How his eyes were betraying him and revealing his darkest thoughts, emotions. How he patted her before-

 _No. It's not time to think about what happened._

She felt her throat constrict, feeling the hot tears building up in her eyes as she observed Sans, barely breathing. Opening her mouth, she breathed,

"Sans, tell me… What is the key to bring happiness for you?"

* * *

She observed Sans as he looked into Frisk's eyes with dark expression.

"you need to promise me that you won't talk to that girl, or approach her in any way." Sans' stern voice made Frisk gulp. What could possibly make a skeleton strong as him to warn about somebody that he barely knows?

"if that- that girl, that thing…" great, she wasn't even a human anymore.

"nothing good can come by talking to that flower. you know that." His voice was surprisingly gentle. Frisk nodded slowly. The girl sighed as she watched the sunset.

And then somebody screamed.

"Sans!" Frisk's action was immediately stopped by Sans. Group of humans were ganging up on a female monster. She was definitely the vulnerable looking one, and Frisk whipped her eyes from the gang to Sans, quickly whispering. Her chocolate eyes filled with compassion. Kindness.

No wonder the skeleton fell for the human.

"You can't leave her there, she'll-"

"leave it." Frisk looked horrified at his words. The figure smiled bitterly.

"But-"

"if i beat them up, it means that they'll find a way to bring that upon us. use it as a weapon to the monsters." His logic was straightforward.

Cruel.

Harsh.

Just like the time when she talked to him.

The girl bit her lips as she contemplated about the possible consequences that she might have to face. Gently touching the glowing hourglass charm with her fingertip, she jumped off from the tree. Holding on to the hood to cover her face.

"SANS!" She definitely heard the astonished exhale of the girl. She also noticed the blue glow in the skeleton's left eye.

Shit. This was bad.

"I don't have any gold, please-"

"Nah, it's not that, old lady." Of course. They just enjoyed the fact that they could pick on an innocent monster. The girl clucked her tongue as she headbutted into the man who seemed to be the leader.

"What the-"

"I'm sorry, but she's my mum." She commented as she put an arm around the petite fluffy monster. The gang regarded her with interest. The monster looked at the girl but didn't dare to open her mouth.

"You're a human."

"What about it?" she could feel the cold gaze on the back of her head. That was Sans. In front of her, the gang were looking at her like a predator on hunt. Shit. Bad.

"You dare-"

"You know, it's pretty gross when you flex like that." She cut the boy's words. His face flushed in embarrassment. Grinding his teeth, the boy took a swipe at the girl. Swiftly, she moved back with the monster. Sans' white orbs narrowed as he watched the girl move.

"impossible." Frisk stared into Sans' eyes. Something was definitely off with him.

"You know; it'd be really helpful if you could help me get this lady out of harm." Cold wind swept through Sans and Frisk. Both flinched in surprise as they whipped their heads around to see where the girl was.

But she was in the same spot.

Sans never felt this uneasy. Squeezing Frisk's shoulder slightly, he told her stay away, his eyes glowing blue. Frisk stepped back as she felt the tingle of electricity in the air. She swore that the amethyst orbs curved into crescent as the hooded figure regarded the two of them.

"I usually don't touch girls, but you know, I think you need a lesson." Buttface (the girl decided to name the 'supposed' leader of the group) popped his neck as he cracked his knuckles. The fluffy monster lady whimpered pitifully as she cowered away from the idiots, staying close to the girl as possible.

"How about we settle this… human vs. human?" Lifting her hands to show that she clearly doesn't want to fight, the girl nudged the monster lady.

"Run as fast as you can to the skeleton over there." There were only three bulky idiots, but having to protect somebody was going to be difficult. The fearful eyes of the fluffy lady tore from the now violet orbs and focused on the skeleton. Sans nodded to her as she broke off running. The boys tried to catch her, but the girl put her legs out in front of them, tripping all three at once.

"woah, lady. just go stay with the kid over there, will ya?" Sans muttered as he lifted the monster lady with his power, frowning as she yelped and flailed around mid-air. His single white pupil dilated as the group of thugs struggled to get up.

"Can we please, resolve this by talking?" The girl murmured as she twirled her hourglass charm with her fingers. The boys growled as they stood up. Taking another swipe at the girl, the buttface grinned cruelly.

"Sorry, you just humiliated us in front of everybody and I don't think I can let that go."

"Figures." Shrugging, the girl clicked her tongue. Ducking as they started to aim for her, the girl jumped away from the gang. Her hood came off and Sans saw the mischief dancing in her dark violet orbs. And then he heard the unmistakable loud voice.

"Hey punk! What brought you here?"

[Undyne, you need to help! Those people over there-] Frisk was frantically pointing at the gang and Undyne's eye narrowed in disapproval.

"Idiots fighting. What does that-"

[The girl saved the lady here and] The magical spear had already materialised and left the hot-headed heroine's hand even before Frisk's sentence finished. Despite Frisk's utterly horrified expression, the spear didn't harm the bulky gang. Sans' eyes widened as he absorbed what had exactly happened.

The girl had thrown herself between the spear and the gangs.

* * *

Out of the list of things that she was planning to do, getting impaled by a magical spear like a fishstick, was definitely not on it. But somehow, she found herself in that situation.

She felt the magical spear impale her. She also felt the spear disappear into thin air as she was left gasping. The pain was, literally, breathtaking. Did she regret pushing the gangs away from the spear?

Truthfully, yes. It hurt like a bitch. But the shit-eating grin on the skeleton's face was now gone, replaced with… confusion?

The gangs looked at her, horrified, as she coughed blood onto the grass. She managed to gasp,

"Watcha looking at? Scram." The bulky idiots scrambled to leave as she put lifted her hood up to sink back into the shadows. Clutching at her hourglass charm desperately, the girl tried to walk away when she was lifted into the air. She felt her body convulse once more with a violent cough.

"Sans, you're hurting her!" Frisk's yell echoed as the girl's eyes closed slowly, head spinning. The last thing she remembered was the blue glow that seemed to dim.

* * *

 **"Aria, baby princess." Melodic voice was murmuring into her head.**

 **The dream was hazy. The girl found herself back to the time when she was young. So young that she could barely understand what was going on. She was scared when she was met with silver white irises that glowed. The black sclera surrounding its' pupils, how his left eye lighted up in cyan and yellow… even she realised that the man wasn't normal.**

 **But mama told her to be nice to him. Her hazel hair and dark chocolate eyes made Aria feel warm. She liked her mama. Mama would sign to her and she tried so hard to mimic the small movements of her hands. Earning gentle laughs that would make her feel sleepy.**

 **Mama would leave the house often. The man – mama's bestfriend, looked after her when mama had to go work. Whenever Aria tried to mimic mama by wriggling her fingers, flexing them in a similar manner as her mama moved them, his sharp eyes softened.**

 **Soon enough, she realised that the man was nice. Not because he was mama's bestfriend, but he talked to her in a manner that no adults would talk to her. Tapping the tip of her nose as she sneezed. Faking to be hurt when she poked his side with her tiny hands.**

 **Taking her away when bad things happened. Like the time when she figured out that her mama wasn't her real mama.**

 **She didn't mean to listen. But when she had a nightmare about a yellow flower that wouldn't stop laughing, the girl found herself carrying a skeleton plushie to her mama office.**

 **Mama was crying. With a photograph on her hand, mama was sobbing, mumbling. Promising to raise her well.**

 **"Aria is a good girl, just like you." She was five when she heard that. She was about to ask about what mama was talking when a cold hand covered her eyes.**

 **"shh, girl, mama needs some time alone." When his big hand wasn't covering her face, Aria tried to murmur something. But his expression…**

 **It was indescribable. Endless hollowness. The playful twinkle gone from his eyes. The dim light in her room shading his left eye. Glowing painfully dim blue. And really, the five-year-old babyself was patting the man's head. Her small hands on his cheeks. Mumbling something about not crying. And then the man had his face burying on her head, the warm liquid tickling her hair as she continued to pat the man without knowing why she was doing that. But she called his name, and he called her name back, gently and ever so sadly that she would never forget.**

* * *

 **A/N: some people might have a vague idea of what's going on now, but hopefully they don't because I like surprises. I like complicating things because I'm a mean, mean writer. Well, time to stuff more things in boxes for moving. Next time!**

 **-HelloSkye-**


	4. Phantom Pain

**A/N: Phew! I'm back with another chapter! I've been busy for about two weeks trying to move and university/college started on top of them. Great timing *thumbs up***

 **Anyway, I was quite surprised to get more favourites & follows by fellow authors/readers - Thanks heaps! The plot is pretty decent (in my imaginary land aka brain) buuuut I honestly don't know how it'll turn out. Thank you to SneaselXRiolu for your reviews! All of your reviews were very interesting and some were even close to my plot *spoiler alert!* :D I always appreciated readers with reviews :) **

**I'll be aiming to upload at least one chapter per 3-5 days! Nag me if I'm late! Let's cut the chitchat and go straight into the story :D**

* * *

Phantom Pain

"-oi, kid." The low growl was the sound that woke her up. Hovering ice blue glow focused as she blinked a few times. And then a sharper, higher-pitched voice cracked her skull with a headache.

"SANS! SHE IS SLEEPING! LEAVE HER ALONE!"

"Papyrus, you're making more noise than anybody here!" Aria opened her eyes gingerly, feeling sick. Gasps, relieved sighs and nervous exhale escaped from the people in the room, but she sat up to raise her hand and retch in the bin beside the bed. She felt the numerous pairs of eyes on her. She felt cold, clammy and sick.

 _Wasn't too bad, though._ She thought to herself, struggling to think positive.

She blinked a few times to clear her head.

"My child, are you okay?" Toriel asked, concern visible in her eyes. Undyne and Papyrus gaped at the girl in interest. Aria felt cold sweat on her forehead.

Shit, this was bad. Almost everybody was in the room. Where was she, anyway?

Feeling uncomfortable at the silence and the attention that was on her, she stood up to leave when she realised that her clothes had changed.

"HUMAN! YOU CANNOT LEAVE!" Papyrus sprang into action, blocking the door. Aria sighed involuntarily, irritated. And then the nausea hit again, making her sway on her feet. Feeling herself fall, Aria closed her eyes.

But there was no impact that she expected. Instead, she felt somebody lifting her. Aria opened one eye to see Sans carrying her. He tucked her into bed again, putting pillows behind her back for support. Toriel patted her forehead gently, wiping the cold beads of sweat with a cloth.

"You're too sick to leave."

[It's okay, we won't hurt you.] Frisk's sign language did not help anything. Instinctively, Aria raised her hand to sign back.

[I know you won't hurt me, but I need to leave.] She heard Frisk gasping.

"May I ask how you know sign language?" Toriel's cautious question made Aria grin bitterly.

"My adoptive mum used sign language." She felt Frisk's eyes staring at her.

"Adoptive? Then where's your-"

"She's dead." Cold silence filled the room again as Aria muttered quietly. Toriel covered her mouth, horrified. Even Undyne seemed uncomfortable at the situation.

"She passed away. When I was sixteen." The calm demeanour of the girl seemed to take others by surprise. Even Sans looked up to meet Aria's eyes.

"How old are you now?"

"Eighteen."

[But you look about the same age as me!] Frisk quickly signed to her, eyes widening in astonishment. Aria grinned slightly. Now everyone was gaping at her.

"Your name?" She chose to ignore that question. Toriel nodded.

"I understand."

"T-Then, where do you live…?"

Alphys stammered quietly, nervously cleaning her glasses. Aria opened her mouth, closed it again to sign to Frisk.

[I wander around. I never live in the same place for a long time.]

"B-but, that's dangerous, you're a-"

"-an eighteen-year-old grown up who can take care of herself." Sans finished, his face expression unexplainable. Alphys tried to say something but decided not to and looked down at the floor, embarrassed. Aria stared at the big boned skeleton with curiosity. He was so different.

"Sans! How could you." Toriel chided Sans and he shrugged like a kid. Frisk snickered at the sight in front of her, earning a well-meant glare from him. Sensing a laugh incoming, Aria hastily coughed to hide it. Toriel's attention snapped right back to her, concern knitting her eyebrows.

"Are you sure you're okay?" Aria quickly nodded, her face flushed in red as she tried to hide her embarrassment.

"You don't look okay, human." Undyne snapped at her sharply, then hesitated.

"Look, I'm sorry for…"

[I understand. It's hard to be a monster on the Surface and I know that you have to protect the monsters. Just bear in mind that hurting a human directly in front of public will not do any good to the monsters.] Toriel nodded in assent as Frisk looked at her incredulously.

[But you know, you can always hunt them down to a private spot. Where nobody will see what happens.] The words that came next were unexpected, though. Toriel's face paled as she pulled Frisk closer to her embrace. Undyne regarded Aria with a piercing gaze as she signed the words effortlessly, expressionless.

"I don't like the way you talk, punk." Aria gave a slight smile to Undyne, nodding.

"You remind me of something I knew. A creepy feeling that I get." Shuddering slightly, Undyne murmured. Aria raised an eyebrow, looking at her questioningly.

"I don't like to think about it. Not that I remember clearly anyway." Aria grimaced slightly and slunk into the blankets.

"What's-"

"Please leave me alone. I want to rest." Toriel opened her mouth again to reply, but decided not to. Nodding at the monsters in the room, she ushered them out quietly.

"Good night." Toriel murmured as she stared at the lumpy blanket silently. Shaking her head, she left the room as the small girl sunk back into the unconsciousness.

* * *

She was crying.

Sobbing pitifully, trying not to make any sounds. All by herself in that dark room with a busted hunk of metal and dusts.

Same thing happened, and she couldn't stop it.

She went back. Told him to run.

He died.

Stopped him from starting the research from the first place.

Still died.

Breaking the horrid machine before he could go further. Attempting to find a different way to tackle the problem.

None of them worked.

She cried, again and again. But every time, her tears were drying faster and faster.

Never did she reset on purpose. She knew what would happen.

The tally counts in her diary increased, but she didn't give up. She went back further. Further. Travelled back to future to see if there were any differences.

Going back again. Trying to find the root of all problems. Taking down notes. Making small changes here and there.

But the outcome was same. The same rumble of the machine. The humanoid monster hurling his body in front of her to take the blast purely by himself as he embraced her tightly. The magic of the machine and the monster flowing into her body and the hourglass charm that she has.

She was tired.

Was this what he felt, too?

Feeling powerless.

Useless.

Worthless.

Wanting to give up.

But she couldn't.

No, she wouldn't.

He was the only one she could bide in. The one who will whisper words that could cheer her up, despite his stupid shit-eating grin and dad puns.

She was saved by the man so many times, and now it was her time to return the favour. So she travelled back further in time. She knew the consequences.

But she would never give up.

* * *

It was still night when Aria woke up. Groaning slightly, she dragged herself out of the bed as she looked around. The room was dark, and the only source of light was the dim moonlight that was peeking through the closed curtains. Exhaling shakily, Aria lightly touched her charm as she gingerly walked out from the room.

The roof had a nice breeze. Even if it was snowing and she was half frozen from the little insulation that the thin pyjama was giving her. Sighing, she extended her arm to open her palm and see a snowflake drop on it to soon melt.

"it is a nice feeling, isn't it?" Gasping at the sudden baritone voice, Aria whipped her head around to face a gasterblaster inches away. She didn't blink an eye.

"Sa – you."

"fancy seeing you here, bud." The cyan glow on his eyes never ceased despite the audible wince of the girl.

"You…"

"what about me, kid? ya looking for a bad time?"

"You're just the same." The kid's words took him by surprise. She knew him?

"what-"

"Let me just tell you this. Your shit-eating grin sickens me." Aria spat harshly, her eyes never leaving the pinpoint pupils of the round skeleton. Confused and worried, Sans opened his mouth to retort to the girl's harsh words.

"kid, you must be mistaken. i never met-"

"You were always like that. Y-you…" Voice cracking, Aria turned away from the round skeleton. Breathing sharply, she murmured into the cold air.

"I don't want to harm you nor your companions. That I will promise. If I ever end up hurting your friends, you can kill me with your own hands." The young melodic voice was too hollow. Too empty for a kid around her age. Sans immediately regretted his decision and put his gasterblaster away to put a hand on her shoulder gently.

"kid, i was only jokin'-" Then it happened. The sharp pain pulsing near his ribcage where the core of his magic was. The girl pushing him away roughly as her eyes filled with a visible emotion that he could put a finger on – terror. She crawled away from him as she winced again, vulnerable as she could be. Sans looked down on her in confusion as the girl exhaled shakily.

"Please don't touch me. You shouldn't."

"kid-"

"Please. I don't want to hurt you." She wasn't lying. The quiver in her voice, her wavering eyes that glowed faintly under the dim silver moonlight was telling him that the girl was telling the truth.

"…alright, buddy. i think it's time for us to head in." shaking his head slightly, Sans extended his hand out to the cowering girl. She looked up at him, reaching out…

…only to stop herself from touching the skeleton monster and standing up by herself.

"I'll be hanging around for a while, but please, don't tell others that I know you… or the others."

"You know others as well?"

"I knew everybody." The distant, fading smile on her lips did a trick to him. How did the humans put it… pulling a string on their heart?

He felt exactly like that.

Not that he had a heart, though.

"…hey, kid. you mind tellin me what happened?" the oddly long pause made his heart- magic-sink. The girl was regarding him with her now almost-black violet orbs. Glazed with something – nostalgia?

"I wish I can, Sans. I really do." And to be honest, he was dying to ask more questions. Whether they had met before. Whether she was there when the kid was running on and about to "save" the monsters from Underworld.

But he couldn't.

Not when he saw her eyes.

Not when he recognised the similar emotions. Endless loneliness. Hollowness. Emptiness. Sorrow that couldn't be replaced. The defeated look.

Almost exactly same as what he had felt.

She was on the brink of tip-over. One more push and she would break.

And as much as Sans was an overprotective psycho, he couldn't bring himself to break the girl who seemed to experience the similar pain as he had.

So he let it go. Just like that.

* * *

 **A/N: Tbh I don't think that was a good ending but if I had to write more this chapter would be extra super long :( Will come back with new surprises :D**

 **'Til then!**

 **-HelloSkye-**

 **\+ I just created a tumblr blog! I think I'll end up scribbling any random ideas but feel free to follow me as I'll be reblogging loads of Undertale stuff :D follow helloskyei :)**


	5. Enveloped in Darkness

**Disclaimer: I do not own Undertale. I own my OC, Aria, but nothing else. All credits for Undertale goes to Toby Fox.**

 **A/N: A day late! Sorry about that, university sucks and I'm only three weeks in. Damn, can't wait for semester break. Anyway, I saw more followers & favourites so thank you so much for all the readers :) I appreciate it! **

* * *

Enveloped in Darkness

Aria couldn't sleep. By the time the sun has started to rise, she was reading one of the textbooks from the bookshelf. Sans, also barely having slept, opened the door to find the young girl immensely absorbed in a thick, hard covered biology textbook. Her amethyst orbs were scanning in a consistent pace; she was a fast reader. Unable to interrupt the kid, Sans slowly closed the door –

"YOU'RE AWAKE!" – almost to jump from Papyrus' loud voice and sigh exasperated. The human was, however, still captivated by the mere textbook. Toriel, yawning and still in her fluffy pyjamas, stopped at the sight of the young girl studying biology at 6 in the morning.

"My child, are you feeling well?" The goat monster smiled genuinely as she placed her hand on the girl's shoulder, only to gasp and quickly take her hand off. That did the trick. Fear in her eyes, the girl recoiled and snug back under the blanket, quietly whispering,

"Please don't touch me." Toriel, clearly shaken by the incident that happened only a few moments ago, knelt down and gently murmured to the girl under the blanket.

"Are you still ill?"

"…No, I'm feeling much better. Thank you." The hesitant and timid voice of the child seemed to melt Toriel's heart.

"Would you like to eat anything?"

"I'm okay, but thank you."

"I CAN COOK YOU SPAGHETTI, HUMAN!"

"Shh, lower your voice! Frisk is still sleeping!"

"And King Fluffybuns too." Undyne walked in with the yellow monster, grinning mischievously. Toriel blushed furious red and the girl poked her head out from the blanket.

"Hello there."

"Looking better, punk. How's your guts doing?"

"Better. Thanks for asking." Undyne seemed to be taken aback at the genuine smile from the girl. Alphys took her glasses off and nervously cleaned it using her lab coat. Aria noticed the jumpy monster and gave out a gentle laugh.

"You don't have to be so nervous, Alphys."

"I – I… O-ooh, I'm r-really sorry, I d-didn't mean to…"

"…I don't want you to feel uncomfortable. Please, it's okay." The gentle tone of the girl seemed to relieve the yellow monster. Undyne patted Alphys affectionately and her cheeks tinged with red.

"Toriel, I-" the girl's voice cracked, and she hastily coughed to hide it. Toriel's ears perked up at the mention of her names and eagerly nodded to the girl.

"What is it, dear?"

"I'll leave as soon as I recover. I promise."

"But-"

"BUT HUMAN! NOT SO SOON!" Aria grimaced at the loud voice of Papyrus, but shook her head slowly.

"I can't stay at one spot for too long."

[Why?] Frisk had entered the room, signing. Aria opened her mouth, but couldn't say anything.

"…I-"

[If you don't have a specific reason, you should stay with us. You saved the powerless monster and I like you.] The blunt, straightforward method of communication that Frisk used made the other girl smile gently.

 _You are just the same. And for that, I can't help loving you._

Blinking back the tears that were threatening to show, Aria smiled brightly. The raven-haired girl extended her hand to the child who was taller than her. Frisk gave a small smile as she gently held her hand.

* * *

"You can walk!" Frisk yelled in glee as she spotted the petite girl standing in front of the school. The children around her ogled at the girl wearing stripes, surprised to hear her yell for the first time. Aria laughed gently as Frisk jumped into the older girl's arms, smiling brightly.

"It's been about two weeks since it happened. Of course I'd be up and about."

[I'm so glad! Does that mean you'll be coming to school with me?]

"Well… I'm technically a university student, so I'm not too sure, Frisk. Should we go back home now?"

"But mum-"

"She told me that she has to prepare things for class tomorrow so it's my job to escort you, my lady." Grinning playfully, Aria half-kneeled in front of Frisk, her hand extended out for the younger girl's hand. Giggling, Frisk held her hand out in sombrely manner, earning a soft chuckle out from the kneeling girl.

"Shall we?"

"I don't see why not."

* * *

"What shall we do with your studies?" Toriel asked, earning a slight grimace from the violet-orbed girl.

"It's okay, Toriel. I…"

"It is not okay to ignore about your education." Aria sighed at her stern voice. She wouldn't be able to keep things hidden.

"I'm not…"

"THERE YOU ARE, HUMAN!" Papyrus barged into the room with Sans tagging along behind him.

"Oh, good. Papyrus, would you help me to persuade-"

"I'm not registered." The words tumbled out of her mouth even before she could stop herself. Toriel stopped, looking through her reading glasses wearily.

"What do you mean?"

"…I'm not registered on the… government program thing. I'm nobody. I don't exist." Silence fell. Toriel regarded the girl with her scarlet eyes.

"I am concerned about how you were raised."

"It's a long story, but please. I can't be registered. I'll-"

 _I'll end up disappearing again anyway._

"…I can't ask you to trust me, but please. I'll do my best to study at home." Aria sent a pleading look towards Sans. Slightly shrugging, the round skeleton stepped forward, gently placing his phalanges on her shoulder.

"hey, what's the big deal? the kid seemed eager to learn when she was reading the textbooks. should be fine." Toriel shot him a stern look as he grinned cheekily. Sighing, she stood up slowly to murmur, "…I'll see what I can do," before leaving the room. Papyrus followed the goat monster, excitedly talking about a new spaghetti that he'll try cooking tonight.

"…so. you got nothin' to say, kid?"

"I'm not a kid, Sans. Stop calling me that." Aria sighed, exasperated. Sans grinned as he sat down on a chair slowly, his pinpoint pupils never leaving the young girl.

"then tell me your name." He noticed the visible flinch of the girl. Raising her eyes from the ivory desk to his eyes, she parted her lips slowly.

"…You don't remember, huh." The nonchalant expression of the girl felt out of place. It was as if she almost knew what was going to happen. Feeling coldness pool in a place where his stomach should be, Sans gulped.

"kid, i told you. i don't-"

"I'm sorry." The next word that tumbled out of the girl's mouth was what unhinged Sans. He closed his eyes.

"you know; I don't understand you. what's so hard about-"

"You won't be able to remember when I leave." The barely audible whisper of the girl hit him like a truck. What did she mean?

"kid, you need to tell me what's going on or i won't be able to trust you." Sans pressed on, ignoring the slight tremble of the girl. A bit more and…

"How about I show you?" The girl disappeared, electricity buzzing in the air. Sans whipped around to see the girl right behind him. She opened her mouth when-

-when he aimed straight for her throat, his eye burning cyan and yellow. Aria could've avoided him whenever, but she chose to stand where she was. Right before his phalanges enclosed on her pale neck, Sans stopped.

"…care to explain about that?"

"I… I choose to be experimented. By a monster."

"its name?"

"I cannot say. Names are very fragile thing… you should know that by experience. Chara."

"you-" The round skeleton's pupils widened as he summoned a gasterblaster out of nowhere. Aria only smiled. Extending her hand, she gently patted the nose of a monstrous weapon.

"Howdy." The gasterblaster nudged at her hand affectionately, earning a shocked intake of breath from Sans. Her melancholic smile seemed so far, so far away…

Sans eyes flashed dangerously as he jumped away from the girl, waving off the weaponised creatures.

"WHAT are you, pal?"

"Your greatest friend." Sans relaxed as he loosened his clenching phalanges. But she parted her lips again.

"Your worst enemy." He tensed again to summon magical bones and to pin her against the wall. His cold phalanges starting to curl around her neck this time, he growled.

"And that choice is not up to me, Sans." The girl breathed out quietly as her glass-like amethyst orbs glistened meeting his empty eyesockets.

"Please don't touch me. I don't want you to get hurt." She didn't struggle. Or put up a fight. She just stayed there, pinned against the wall with magical bones around her. Sans pulled back, sharply clicking his phalanges. The bones disappeared. However, the marks on the wall was clearly visible.

"…damn, toriel's gonna ask me-" Waving her hands in front of the damaged wall, electricity buzzed in the room again. The wall mended like magic, and his lifted his eyebrow at the petite girl for another explanation.

"…I can… repair things. That's one of my magic." Her eyes were shifting constantly. Sans lifted his eyebrow again, his baritone voice chilly.

"you suck at lying, kiddo."

"…I know." Aria grinned weakly. Sitting back down again, she motioned Sans the same. He sat down hesitantly, opening his mouth to ask,

"so, what were you doing with that bloody flower?"

* * *

 **"…** **mum couldn't have. She's strong. She's determined. She's-"**

 **"…** **I'm sorry." The furry, humanoid monster pulled Aria into an embrace as she apologised. The girl stood still, recalling the events that had happened just few hours ago.**

 **She was the first to be on the scene of dreadful sin. Her mum's office, splattered with still warm blood. Her mum lying in the pool of blood, almost cold, almost-**

 **She told her not to cry. She also told her that she'll be able to see her again, well and healthy. She promised, right? And she never broke her promise, right?**

 **…** **so much for a promise.**

 **Aria demanded to see her mum. The monsters stopped her. She resisted. She was determined to see her mum.**

 **And when she did, she was almost impassive. Almost.**

 **Covered with a white cloth, she was so very still. Hands trembling slightly, Aria pulled the cloth that was covering her face.**

 **It was beautiful. If anybody could look so peaceful before their death, it was only her mum. Dark circles around her closed eyes, long dark lashes, the still soft smile that was etched upon her face…**

 ** _She couldn't be dead, right? She's only sleeping. They're trying to scare me._**

 **Laughing hollowly, she reached for her mum's hand tentatively.**

 **It was cold.**

 ** _Her hands are usually cold, idiot. Feel her pulse!_** **The voice in her head scolded her. Two thin, pale fingers touched the woman's neck where her pulse should be.**

 **Nothing.**

 **And then it hit her like a truck. She really was dead.**

 **No more welcome smile when she gets home. No more spaghetti that she cooks. No more striped clothes that she should get for her.**

 **"…** **.Hah…" Aria exhaled shakily. She held her mum's hand and placed in on her cold cheek, kneeling down.**

 **"** **Mum, c'mon, it's not funny. Wake up?"**

 **Empty room.**

 **Empty voice.**

 **Empty heart.**

 **She demanded again.**

 **"** **Wake up! Please?" The girl rubbed the cold hand on her cheek, now pleading.**

 **She's still alive.**

 **I refuse to believe this.**

 **"** **MUM. Please…" The tears that were held back broke freely as the pale girl continued to beg and plead for her mum to open her eyes. The silent sobbing crescendo-ed into a loud cry as she clung on to last hope, desperately trying to warm the cold hand with her hot tears.**

* * *

 **"** **... Please, give my soul to Flowey when I… you know, in any case." Aria read out loud, her voice empty. The few monsters in the room gasped audibly.**

 **"** **Flowey- but-" she didn't know what Flowey is. Mum never mentioned anything like that to her. But she knew that mum wouldn't do something stupid that will cause harm to any of her friends, or herself. Aria closed her eyes wearily.**

 **"…** **If it's mum's will, then do whatever she says." Clarifying what she wants, Aria left the room. She desperately wanted her mum back. She was only fifteen.**

* * *

 **"** **Howdy?" an uncertain voice echoed from outside. Aria, hugging her knees to chest, blinked slowly. The completely destroyed office was now free of bloodstains, but the sickly metallic scent remained the same.**

 **"…** **um. Howdy?" Hesitantly standing up, Aria walked up to the door to open it. There stood a goat monster, still young. Short. Probably younger than her.**

 **"…** **I don't want any visitors. Ple-"**

 **"…** **Well, I'm Asriel, aka Flowey…" The voice trailed off timidly as he finished the sentence. Aria recalled the name Flowey and regarded him silently.**

 **"…** **I guess the experiment was a success, then." The still impassive, still and hollow voice seemed to scare Asriel. Stammering quietly, he stared the ground, his goat eyes tearing up.**

 **"** **I… I'm really sorry to hear about your mum. I knew her, you know-"**

 **"** **And you got her soul. "**

 **"** **I-"**

 **"** **Get out." Her voice was too cold that it even scared herself. Asriel, stumbling, cried,**

 **"** **Wait! Plea-"**

 **"** **I don't want to see anyone. Please tell that to… your friends." Closing the door harshly, Aria leaned back on the door, sliding quietly. Curled into a ball again. The sound of thunder echoed from far distance. Slowly being enveloped by the darkness, Aria whispered,**

 **"…** **Mum, what do I do?"**

* * *

"kid. pal. kiddo. baby?" The baritone voice tinged with concern and playfulness took her by surprise.

"Gross, baby?"

"you were out daydreaming for about ten minutes. care to share?"

"No thanks."

"c'mon, caring is sharing."

"Pfft." Snickering, Aria met the white pinpoint pupils again. She exhaled slowly.

"I'm going to save Flowey. No, not just Flowey. I will save everyone."

* * *

 **A/N: And here's the third chapter! Thank you so much for the reviews! If I was to answer, SneaselXRiolu: your reviews are always interesting! I even incorporated some of your guesses to my fanfic (in my head it's going to work beautifully so yay!). Can't wait for more reviews from you :) ngrey651: personally, it does feel a bit** **clichéd, but there's a reason for why :D I won't let Aria to keep hiding so don't worry :)**

 **Reading this chapter fills you with DETERMINATION.**

 **Continue?**

 **-HelloSkye-**


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